Membrane dust-pumping system

ABSTRACT

A diaphragm pump is provided for the pressurized delivery of dusts in a dust feeding device. The diaphragm pump includes a storage hopper which is subjected to inert gas at ambient pressure and which serves for the storage of the dust. A sluicing vessel is provided which is connected via an inlet in the upper region, via a shut-off fitting and via a dust supply line to the dust store of the storage hopper, and is connected via an outlet in the lower region and via a shut-off fitting to a high-pressure device. A diaphragm is mounted in the sluicing vessel. An expansion line is provided, one end of which is connected via a filter element to the sluicing vessel and into which a shut-off fitting is incorporated. The diaphragm pump includes charging line which is connected via a filter element and via a shut-off fitting to the sluicing vessel.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is the US National Stage of International Application No. PCT/EP2012/056302, filed Apr. 5, 2012 and claims the benefit thereof. The International Application claims the benefits of German application No. 102011007066.4 DE filed September Apr. 8, 2011. All of the applications are incorporated by reference herein in their entirety.

FIELD OF INVENTION

The invention relates to a diaphragm pump for the pneumatic pressurized delivery of dusts, and to a method for the pressurized delivery of dusts in a dust feeding device.

BACKGROUND OF INVENTION

The subject matter of the application relates to a diaphragm-type dust pump system which is capable of feeding dusts from a vessel operated at ambient pressure into a system that operates at elevated operating pressure.

In many technical processes, it is necessary for dusts to be delivered pneumatically at an elevated pressure level. Examples include carbon dust gasification with a pneumatic dust supply at gasification pressures up to 4 MPa (40 bar) and above, pneumatic combustion dust injection into tuyeres of shaft furnaces such as blast furnaces for generating raw iron, or else the pneumatic delivery of dusts over large distances, wherein the delivery receptacles must be charged to the operating pressure required for overcoming the delivery line pressure loss.

In the prior art, in particular in the case of applications with relatively high operating pressures, such as are necessary in the case of carbon dust pressurized gasification, use is made of a system of feeding sluices, as described in “NOELL-KONVERSIONSVERFAHREN ZUR VERWERTUNG UND ENTSORGUNG VON ABFÄLLEN” [NOELL CONVERSION METHODS FOR THE UTILIZATION AND DISPOSAL OF WASTES”], EF-Verlag für Energie- and Umwelttechnik GmbH, 1996, page 34. Here, the combustion dust is supplied, from a storage hopper at ambient pressure, to feeding sluices which are subsequently charged to the operating pressure of the dosing or delivery receptacle arranged therebelow by the supply of a condensate-free inert gas. When there is a demand for dust in the dosing or delivery receptacle, the combustion dust which is now at the required pressure is transferred by gravity-delivery action from the feeding sluices into the dosing or delivery receptacle.

In the lower part of the dosing or delivery receptacle, a partial fluidized bed is generated by the supply of a likewise inert fluidizing gas, into which partial fluidized bed one or more dust delivery lines are immersed. Through the application of a pressure difference between the dosing receptacle and the receiver of the combustion dust, for example a gasification reactor, the combustion dust flows to said receiver as a dust gas suspension with a high solids content. This delivery and dosing technology is characterized by numerous disadvantages. These relate firstly to the discontinuous operation of the feeding sluices. The feeding sluices, after being filled with dust in the unpressurized state, are charged to the required operating pressure by the supply of an inert gas, are evacuated into the dosing or delivery receptacle at said pressure, and are re-filled with dust after being expanded to ambient pressure. In the case of high dosing rates, multiple feeding sluices are required for a more or less continuous supply of dust to the dosing receptacle. Further disadvantages are the high gas requirement for the charging of the feeding sluices, and the outlay for the cleaning of the expansion gas.

DE 103 53 968 A1 has already proposed a delivery device and a delivery method for the delivery, with little or no fluidizing compressed air, of coating powders, wherein the pressure increase of a self-priming pump is effected by the exertion of hydraulic load on a hose-type diaphragm.

CH 466 134 A discloses a method and a device for the pneumatic delivery of material in dust and granular form, wherein the pressurization of the material to be delivered takes place in a diaphragm pump by the action of force on the diaphragm. A gas-permeable diaphragm for the injection of purging gas may be arranged in the pump chamber. The stroke chamber of the diaphragm is configured such that only minimal gas passage gaps are provided, so as not to increase in size the dead volume and thus reduce the attainable pressure. Said diaphragm pump is characterized by delivery with low gas flow rates in relation to known methods.

SUMMARY OF INVENTION

The invention is based on the problem of improving a dust feeding system such that the sluices and the problems resulting from the sluice expansion can be eliminated and the inert gas requirement for the feeding of dust into a pressurized system is significantly reduced.

The problem can be solved as in DE 10 2008 009 679 A1. Here, use is made of pistons as displacement bodies. This however has the disadvantage that intense wear of the piston and of the piston seal is to be expected in the case of high pressure differences and fine dust. Furthermore, intense wear of the shut-off fitting at the inlet of the high-pressure device is to be expected owing to the backward charging of the pipe line section from the dust-filled high-pressure device. It is also to be assumed that compaction of the dust is possible as a result of possible abrupt charging of the dust chamber from one side.

The problem is solved by the features of the independent claim(s).

The invention yields a considerable reduction in the requirement for charging gas.

In a further refinement of the diaphragm pump according to the invention, the other end of the expansion line (10) is connected to the storage hopper (14). Said measure makes it possible for the dust in the storage hopper to be charged with inert charging gas with little outlay.

In a further refinement of the diaphragm pump according to the invention, the dust is delivered by gravity-driven delivery action into the sluicing vessel (1) arranged below the storage hopper. Said measure makes it possible for the sluicing vessel (1) to be filled with dust with little outlay.

In further refinement of the diaphragm pump according to the invention, the filter element is adapted in terms of its shape to the volume omitted by the deflection of the diaphragm. Said measure results in a reduced minimum volume of the dust region.

In a further refinement of the diaphragm pump according to the invention, the filter elements (5) are of large-area form. As a result of the associated introduction of the charging gas at a low flow speed, the dust is prevented from being compacted in the sluicing vessel (1).

In a further refinement of the diaphragm pump according to the invention, the charging line (12) is connected to the high-pressure device (8). In this way, an excess of gas in the high-pressure device (8) is avoided.

In a further refinement, the pressure difference between the storage hopper and the high-pressure device is overcome by multiple feeding devices arranged one below the other. Said measure results in a splitting-up of the pressure difference between the storage hopper and high-pressure device, an increase in the pressure difference that can be overcome, and an increase in pressure safety.

In a further refinement, the dust is delivered from the storage hopper into the high-pressure device by means of multiple feeding devices arranged in parallel. By means of said measure, an increased dust delivery rate is attained.

In a further refinement, the feeding devices operate in a phase-offset manner. By means of said measure, the delivery process is homogenized.

The discontinuous sluicing process corresponding to the prior art is replaced by a virtually continuously operating dust feeding system.

In a further refinement, in each case two feeding devices operate in tandem such that the charging of one sluicing vessel (1) is performed at the same time as the volume displacement of the other sluicing vessel by the diaphragm (2). By means of said measure, the effects on the pressure regime of the high-pressure device are reduced.

Through the selection of a suitable size ratio between the sluicing vessel (1) and the high-pressure device (8), the volume displacement in the sluicing vessel takes place without the pressure regime of the high-pressure device (8) being significantly influenced.

Further advantageous refinements of the invention are specified in the subclaims.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will be explained in more detail below as an exemplary embodiment, to an extent necessary for comprehension, on the basis of a figure, in which:

FIG. 1 shows a dust feeding system for a system for carbon dust delivery into a high-pressure device.

DETAILED DESCRIPTION OF INVENTION

The dust for feeding into a high-pressure device (8) which operates at elevated operating pressure is situated within a storage hopper (14) arranged above the dust feeding system. A sluicing vessel (1) above the high-pressure device is filled with dust by gravity-delivery action. Here, the delivery of the dust may be assisted by the retraction of the diaphragm (2), which may be manufactured from elastic material and/or may be flexible. The gas hereby displaced from the sluicing vessel is discharged via the open shut-off fitting (11) in the expansion line (10). Subsequently, the shut-off fitting (7) in the carbon dust supply line and the shut-off fitting (11) in the expansion line are closed. Subsequently, the sluicing vessel (1) is brought to the required pressure by means of the introduction of high-pressure inert gas via the shut-off valve (13), which is to be opened, in the charging line. By means of the slow introduction of the charging gas via the filter elements (5) which are of large-area design, the dust is prevented from being compacted in the sluicing vessel (1). When the pressure in the sluicing vessel (1) reaches the pressure of the high-pressure device (8), the shut-off fitting (13) in the charging line is closed, and the shut-off fitting (9) at the inlet of the high-pressure device is opened. By gravity-driven delivery action, the dust is delivered out of the sluicing vessel (1) into the high-pressure device (8). Here, the delivery may be assisted by the displacement movement of the diaphragm (2). The deflection of the diaphragm is effected by means of the introduction of hydraulic fluid via the hydraulic line (4). The hydraulic deflection of the diaphragm (2) has the effect that said diaphragm operates in a pressure-relieved manner. When the dust has been completely evacuated into the high-pressure device (1), the dust chamber volume of the sluicing vessel (1) is minimized by virtue of the diaphragm (2) being fully deflected. By means of said measure, the highly pressurized inert gas remaining in the sluicing vessel (1) after the dust delivery process is greatly minimized, and thus the consumption of high-pressure inert gas by the dust feeding system is greatly reduced. Subsequently, the shut-off fitting (9) at the inlet of the high-pressure device is closed.

The inert gas remaining in the sluicing vessel is then expanded toward the storage hopper (14) by virtue of the shut-off fitting (11) in the expansion line being opened.

When pressure equality between the sluicing vessel (1) and storage hopper (14) is attained, one working cycle is ended and the following cycle can be started.

To attain high feed rates, it is possible for multiple feeding devices to be operated in parallel for the supply to a dosing or delivery receptacle. In FIG. 1, two such feeding devices are illustrated by way of example.

In the lower part of the dosing or delivery receptacle (1), a partial fluidized bed is generated by the supply of a fluidizing gas according to prior art, from which partial fluidized bed a feed is provided to one or more delivery lines. To maintain the required pressure difference with respect to the respective consumer or receiver of the material, in dust form, for delivery, the dosing or delivery receptacle has gas supplied to it, or excess gas discharged therefrom, in a known manner.

The invention will be explained below on the basis of two examples. This explanation is based on FIG. 1.

EXAMPLE 1

It is the intended object for a combustion dust flow rate of up to 8 Mg/h to be supplied, by means of a system for carbon dust injection, to a blast furnace for the generation of raw iron. For this purpose, it is the intention to use a dosing receptacle equipped with two feeding devices, as illustrated in FIG. 1. Taking into consideration a bulk density of approximately 0.6 Mg/m³, the result is a bulk volume of approximately 13.5 m³ to be fed per hour. If it is assumed that each of the two feeding devices performs one stroke per minute, in the case of a diameter of the diaphragm (2.1) of 1 m, the required volume is attained with a stroke height (2.2) of 0.28 m.

In this example, the required operating pressure of the dosing receptacle is of the order of magnitude of 0.5-0.6 MPa (5-6 bar).

EXAMPLE 2

This example will be explained on the basis of FIG. 1.

It is the object for gasification dust to be supplied, by means of a pneumatically operating dust feeding system, to a reactor for the gasification of combustion dust at an operating pressure of for example 4 MPa (40 bar). The reactor power is 500 MW. The carbon dust flow rate to be introduced for this purpose is approximately 75 Mg/h. In the case of a bulk density of 0.6 Mg/m³, this corresponds to a feed rate of 125 m³ of carbon dust bulk per hour.

In the present example, in each case six feeding devices are selected. If it is assumed that each feeding device performs one stroke per minute, in the case of a diameter of the diaphragm (2.1) of 1.5 m, the required volume is attained with a stroke height (2.2) of 0.4 m.

The expression “dust” used in the description is to be understood generally to mean bulk material, in particular dusts of different grain size distribution, composed of inorganic or organic materials such as carbon of different coalification degree, biomasses or dry residual and waste materials, or else chalk and fine sand.

The expression “inert gas” used in the description is to be understood to mean an O2-free gas, in particular nitrogen, carbon dioxide, natural gas or else a synthesis gas from a downstream gasification system, and any mixtures of these.

LIST OF REFERENCE NUMERALS

1 Sluicing vessel, pressure-resistant pump housing

2 Diaphragm

2.1 Diameter of the diaphragm

2.2 Stroke height of the diaphragm

3 Diaphragm position at maximum displacement

4 Hydraulic supply and discharge line

5 Filter element for charging and expansion

6 Dust supply line from the storage hopper

7 Shut-off fitting in the dust supply line

8 High-pressure device

9 Shut-off fitting at the inlet of the high-pressure device

10 Expansion line to storage hopper

11 Shut-off fitting in the expansion line

12 Charging line

13 Shut-off fitting in the charging line

14 Storage hopper

15 Dust region

16 Impingement medium region 

1-29. (canceled)
 30. A diaphragm pump for the pressurized delivery of dusts in a dust feeding device, the diaphragm pump comprising: a storage hopper which is subjected to inert gas at ambient pressure and which serves for the storage of the dust, a sluicing vessel whose volume is separated in a gas-tight and liquid-tight manner by a diaphragm into a dust region and an impingement medium region, wherein the dust region of the sluicing vessel is connected via an inlet in the upper region, via a shut-off fitting and via a dust supply line to the dust store of the storage hopper, and is connected via an outlet in the lower region and via a shut-off fitting to a high-pressure device, wherein the impingement medium region is connected to a supply and discharge line for an impingement medium, an expansion line, one end of which is connected via a filter element to the sluicing vessel and into which a shut-off fitting is incorporated, a charging line which is connected via a filter element and via a shut-off fitting to the sluicing vessel, wherein the shut-off fitting in the dust supply line is configured to be opened for such a length of time that the dust chamber of the sluicing vessel is filled with dust, wherein the inert gas displaced out of said sluicing vessel in the process can be discharged via the expansion line and the open shut-off fitting, wherein after the closure of the shut-off fitting in the dust supply line and of the shut-off fitting in the expansion line, the dust chamber can be charged with high-pressure inert gas to the pressure of the high-pressure device via the charging line and via the open shut-off fitting , wherein after the operating pressure of the high-pressure device is reached, the pressurized dust passes, by gravity-driven delivery action, into the high-pressure device via the open shut-off fitting at the inlet of the high-pressure device, wherein after the transfer of the dust out of the sluicing vessel into the high-pressure device, the diaphragm can be moved into the position of maximum displacement, and subsequently the shut-off fitting to the high-pressure device can be closed.
 31. The diaphragm pump as claimed in claim 30, wherein the other end of the expansion line is connected to the storage hopper.
 32. The diaphragm pump as claimed in claim 30, wherein in that the diaphragm is in the form of a pot-shaped diaphragm.
 33. The diaphragm pump as claimed in claim 30, wherein the diaphragm is in the form of a plate-shaped diaphragm.
 34. The diaphragm pump as claimed claim 30, wherein the diaphragm is in the form of a hose-shaped diaphragm.
 35. The diaphragm pump as claimed in claim 30, wherein the diaphragm is in the form of a piston with rolling diaphragm.
 36. The diaphragm pump as claimed in claim 30, wherein the diaphragm is substantially circular.
 37. The diaphragm pump as claimed in claim 30, wherein the filter element is adapted in terms of its shape to the volume omitted by the deflection of the diaphragm.
 38. The diaphragm pump as claimed in claim 30, wherein the filter element is of large-area form.
 39. The diaphragm pump as claimed in claim 30, wherein the filter element substantially has an annular shape.
 40. The diaphragm pump as claimed in claim 30, wherein the impingement medium is in the form of a hydraulic liquid.
 41. The diaphragm pump as claimed in claim 30, wherein the impingement medium is in the form of a gas.
 42. The diaphragm pump as claimed in claim 30, wherein the charging line is connected to the high-pressure inert gas supply.
 43. The diaphragm pump as claimed in claim 30, wherein the charging line is connected to the high-pressure device.
 44. The diaphragm pump as claimed in claim 30, wherein multiple feeding devices are arranged for delivering dust into the high-pressure device.
 45. A method for the pressurized delivery of dusts in a dust feeding device, wherein the dust feeding device includes: a storage hopper which is subjected to inert gas at ambient pressure and which serves for the storage of the dust, a sluicing vessel which is connected via an inlet in the upper region, via a shut-off fitting and via a dust supply line to the dust store of the storage hopper, and is connected via an outlet in the lower region and via a shut-off fitting to a high-pressure device, a diaphragm mounted in the sluicing vessel, an expansion line, one end of which is connected via a filter element to the sluicing vessel and into which a shut-off fitting is incorporated, a charging line which is connected via a filter element and via a shut-off fitting to the sluicing vessel, the method comprising: opening the shut-off fitting in the dust supply line for such a length of time that the dust chamber of the sluicing vessel is filled with dust, discharging the inert gas to be displaced out of said sluicing vessel in the process via the expansion line and the open shut-off fitting, after the closure of the shut-off fitting in the dust supply line and of the shut-off fitting in the expansion line, charging the dust chamber with high-pressure inert gas to the pressure of the high-pressure device via the charging line and via the open shut-off fitting, after the operating pressure of the high-pressure device is reached, passing the pressurized dust by gravity-driven delivery action into the high-pressure device via the open shut-off fitting at the inlet of the high-pressure device, after the transfer of the dust out of the sluicing vessel into the high-pressure device, moving the diaphragm into the position of maximum displacement, and subsequently closing the shut-off fitting to the high-pressure device.
 46. The method as claimed in claim 45, wherein the dust is delivered by gravity-driven delivery action into the sluicing vessel arranged below the storage hopper.
 47. The method as claimed in claim 45, wherein the gravity-driven delivery of the dust out of the storage hopper into the sluicing vessel arranged below is assisted by an opening movement of the diaphragm.
 48. The method as claimed in claim 45, wherein the dust is delivered by gravity-driven delivery action into the high-pressure device arranged below the sluicing vessel.
 49. The method as claimed in claim 45, wherein the gravity-driven delivery of the dust out of the sluicing vessel into the high-pressure device arranged below is assisted by a displacement movement of the diaphragm.
 50. The method as claimed in claim 45, wherein the ratio between the displacement volume of the diaphragm and the dead volume in the sluicing vessel is selected such that, after the refraction movement of the diaphragm, the remaining gas quantity is present at approximately ambient pressure.
 51. The method as claimed in claim 45, wherein the gas quantity remaining in the sluicing vessel is expanded to ambient pressure via the filter elements and via the open shut-off fitting in the expansion line.
 52. The method as claimed in claim 45, wherein the process is continued cyclically.
 53. The method as claimed in claim 45, wherein the diaphragm is deflected hydraulically.
 54. The method as claimed in claim 45, wherein the pressurized dust passes together with the charging gas into the high-pressure device and is subsequently supplied to a dust consumer.
 55. The method as claimed in claim 45, wherein the pressurized dust passes together with the charging gas into the high-pressure device, which is in the form of an injector, and is supplied to a consumer by injection of delivery gas.
 56. The method as claimed in claim 45, wherein multiple feeding devices are provided which operate in a phase-offset manner on a common high-pressure device.
 57. The method as claimed in claim 45, wherein in each case two feeding devices operate in tandem such that the charging of one sluicing vessel in one feeding device is performed at the same time as the displacement movement of the diaphragm in the other feeding device.
 58. The method as claimed in claim 45, wherein the pressure difference between the storage hopper and the high-pressure device is overcome by multiple feeding devices arranged one below the other. 